Load-bearing characteristics and energy evolution of fractured rock masses after granite and sandstone grouting

Experiments on grouting-reinforced rock mass specimens with different particle sizes and features were carried out in this study to examine the effects of grouting reinforcement on the load-bearing characteristics of fractured rock mass.The strength and deformation features of grouting-reinforced rock mass were analyzed under different loading manners;the energy evolution mechanism of grouting-reinforced rock mass specimens with different particle sizes and features was investigated;the energy dissipation ratio and post-peak stress decreasing rate were employed to evaluate the bearing stability of grouting-reinforced rock mass.The results show that the strength and ductility of granite-reinforced rock mass(GRM)under biaxial loading are higher than that of sandstone-reinforced rock mass(SRM)under uniaxial loading.Besides,the energy evolution characteristics of grouting-reinforced rock mass under uniaxial and biaxial loading mainly could be divided into early,middle,and late stages.In the early stage,total,elastic,and dissipation energies were quite small with flatter curves;in the middle stage,elastic energy increased rapidly,whereas dissipation energy increased slowly;in the late stage,dissipation energy increased sharply.The energy dissipation ratio was used to represent the pre-peak plastic deformation.Under uniaxial loading,this ratio increased as the particle size increased and the pre-peak plastic deformation of grouting-reinforced rock mass became larger;under biaxial loading,it dropped as the particle size increased,and the pre-peak plastic deformation of grouting-reinforced rock mass became smaller.The post-peak stress decline rate A_(v) was used to assess the post-peak bearing performance of grouting-reinforced rock mass.Under uniaxial loading,parameter A_(v) exhibited reduction as the particle size kept increasing,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was greater,and the bearing capacity was greater;under biaxial loading,A_(v) increased with the particle size,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was low and the bearing capacity was reduced.The findings are considered instrumental in improving the stability of the roadway-surrounding rock by granite and sandstone grouting.

从河流埋藏环境看丁村遗址群的文化性质——与张森水先生商榷

丁村遗址是我国旧石器时代中期文化的重要代表。晚近有一种观点将丁村 54∶1 0 0和 54∶1 0 2地点的石制品组合从丁村文化范畴中分离出来 ,归入以周口店第 1地点为代表的“中国北方旧石器时代工业”中 ,而将该遗址的其它地点划归“丁村文化B组工业”。本文认为丁村文化是一个不可分割的整体 ,而且丁村遗址是一个经过河流搬运埋藏的遗址群 ,各地点之间石制品大小和类型等特点的差异主要是由河流搬运埋藏的特点所造成的 ,并不是两种“工业”

西漢的大土地經營和奴婢勞動--以對香港中文大學文物館所藏簡牘《奴婢廩食粟出入簿》的分析爲中心

本文通過對香港中文大學所藏西漢簡牘《奴婢廩食粟出入簿》的分析,探討漢代奴婢制大土地經營問題。筆者詳細分析《奴婢廩食粟出入簿》中出現的“田官”,元鳳二年“田官”壽納入穀物的“官”的性質,以月爲單位領取口糧的奴婢性别、年齡結構、年齡群的調整時期、年齡的大小與口糧的遞减率等問題。在此基礎上,論证此文書爲民間大土地經營者書寫的私人文書。《居延漢簡》、《敦煌漢簡》所見同時代官府文書中,幾乎不存在同時記録穀物量的大小石、以參(1/3斗)爲單位的量器的使用、“少半升”、“用粟”等,可進一步確認該文書爲私人文書。但不能以此夸大漢代農業生産中奴隸勞動所占的比重。大土地奴隸制經營可能祇是在不易確保佃户數量而又能廉價購買奴婢的情况下實行的生産方式,可以將奴婢的以“家”爲單位組成的特徵與部曲的起源相聯繫起來理解。

秦汉刍稿税计量单位考释——以简牍为中心

据简牍材料,秦汉刍稿税征收中所使用的计量单位主要有“束”“石”“钧”“斤”“斗”等。其中,“束”既可作计量单位,也有刍稿测算标准之用;“石”既可作重量也可作容量单位。笔者推测,“石”作容量单位计量刍稿时,与粮食计量体系中量麦的折算比例是一致的,二者同为3:2;刍稿计量时出现“小石”与“大斗”连用的情况,这与粮食计量有所不同。基于此,秦汉刍稿税计量系统中可能也存在和两石计量相类似的大小石关系。此外,计量刍稿用容量“石”折换重量“石”是为满足现实需要。

Recent advances in naphtha catalytic cracking by nano ZSM-5:A review

This review discussed the use of nano ZSM‐5 in naphtha catalytic cracking. The impact of nano ZSM‐5 on product selectivity, reaction conversion and catalyst lifetime were compared with micro‐sized ZSM‐5. The application of nano ZSM‐5 not only increased the catalyst lifetime, but also gave more stability for light olefins selectivity. The effects of the reaction parameters of temperature and feedstock on the performance of nano ZSM‐5 were investigated, and showed that high temperature and linear alkanes as feedstock improved light olefin selectivity and conversion.

Small sphincterotomy combined with papillary dilation with large balloon permits retrieval of large stones without mechanical lithotripsy

AIM： TO introduce a new method： small endoscopic sphincterotomy （ES） combined with endoscopic papillary large balloon dilation （SES ＋ EPLBD） to treat patients with large biliary stones.METHODS： Retrieval of large biliary stones was performed in 88 patients. Mean stone size was 14 ± 3 mm and mean number of stones was 2.5 ± 3.5. Firstly, ES with a small incision was performed. Next, endoscopic papillary dilation was performed with a large balloon to slowly match the size of the bile duct. Stones were then retrieved from the biliary duct with a balloon and a basket.RESULTS： Stone retrieval was successful in all cases except one cystic duct stone case without the need to crush large stones. Mean procedure time was 30 ± 5 min. Dilating the papillary orifice with a large balloon made it possible to remove large stones smoothly without crushing them. After dilation with the large balloon, there were some instances of oozing, but no perforations. One instance of post-procedural pancreatitis （1%） occurred. CONCLUSION： SES ＋ EPLBD was effective for the retrieval of large biliary stones without the use of mechanical lithotripsy.

Pressure from surrounding rock of three shallow tunnels with large section and small spacing

With the increasing traffic demand, the closely built three or more tunnels with large section play a significant role in the tunnel construction. However, the interaction among tunnels has important influences on the security and economy of tunnel engineering, and the calculation of pressure from the surrounding rock during the excavation is one of the problems that need to be solved urgently. Based on the practical engineering of three tunnels, the load model of three tunnels was proposed in consideration of the interaction and excavation sequence between tunnels. In comparison with the load model of single tunnel, the construction mechanical characteristics of the three tunnels were analyzed. The results show that the rock pressure of three tunnels calculated by the current tunnel design code is not reliable, and the interaction force increases with the spacing between tunnels.

Method for Control of Particle Size and Morphology of Paraffin/Polystyrene-Divinylbenzene Microcapsules

Microencapsulation of phase change materials(Micro PCMs) has been paid special attention because of their extensive applications in saving and releasing energy. Micro PCMs containing paraffin with a melting point of 55 ℃ in polystyrene-divinylbenzene(P(St-DVB)) were prepared by suspension-like polymerization. The characterization of microcapsules by FTIR, DSC and TG proved that paraffin had been successfully encapsulated and the proportion of encapsulated paraffin was 49.8%—58.5%. The effects of polyvinylpyrrolidone(PVP) with different molecular weights serving as the suspension stabilizer were investigated in detail. The results illustrated that the type of PVP had a significant influence on the particle size of Micro PCMs. The average diameter of Micro PCMs decreased with an increasing molecular weight of PVP. Moreover, the crosslinker-postaddition method was adopted in this study to improve the morphology of P(St-DVB) Micro PCMs. SEM images showed that when the DVB was added at the 2nd hour of polymerization the morphology of obtained P(St-DVB) Micro PCMs exhibited good sphericity since it could avoid the influence of cross-linker agent during the nucleation period.

Particle Size and Shape of On-road Suspended Coarse Dust in the Shijiazhuang City, China

The particle size and shape measured by image analysis is helpful to discuss the human health effects of particulate beside the aerodynamic scale. To explore the size and shape features of particle suspended in the road environment, this research selected 12 bus stations as the sampling sites along the main road in the air polluted city Shijiazhuang, China, where a Car-Free Campaign had been carried out. We hung 2 slides covered with a layer of petroleum jelly to collect suspending particles for 24 hours at each sampling site, and measured the particles size and shape parameters with the Particle Size Analyzer of CIS-50. The results show that the average particle size by the equivalent area diameter is around 10 μm, the size distributions are multi-modal with wide span, demonstrating that coarse dust suspended on road derived from several particle sources. Most of the particles suspended are square or square-like in shape with rugged border. Compared the samples of ordinary days and of the Car-Free day, the size and shape features vary little, inferring the ineffective results for the particle control of the Campaign. There is certain relationship between particle size and shape. The number percent of PMs-E （particulate matter with equivalent area diameter beneath 5 pro） is positively correlative with the number percent of particles of square or square-like shape, and negatively correlative with that of round or round-like shape. This relationship pattern in the road environment is contrary to the situations in the upper atmosphere, inferring different transportation and source emission mechanism influences.

Hydrothermal Synthesis and Properties of Y-zeolite-containing Composite Material with Micro/mesoporous Structure

A Y-zeolite-containing composite material with micro/mesoporous structure had been synthesized from kaolin by means of the in-situ crystallization method. The obtained samples were investigated by XRD and BET methods. Evaluation of catalytic activity of both the commercial Y-zeolite and the novel Y-zeolite-containing composite material was carried out in the pulse micro-chromatography platform with two probe molecules of different molecular sizes： VGO feedstock and 1,3,5 tri-isopropyl benzene. It was found that the Y-zeolite-containing composite material was richer in external surface and meso-/macro-pores; the Y-zeolite-containing composite material demonstrated a smaller rate of deactivation compared to the commercial Y-zeolite.

秦、西汉容量“石”诸问题研究

"石"是秦及西汉谷物管理中常见的容量单位和量器,王莽以后才基本被"斛"所取代。"石"作为最高容量单位在当时是与国家规定的最高容量单位"桶"并行使用的。容量"石"来自于10斗米与重量1石()之禾价值相等的规律,故10斗米可称为1石"标准米"。"标准米"在定义容量单位、建立谷物管理系统中起了关键作用。"大小石"不仅出于粟与米之间5∶3的大小单位的比例关系,而且是官粮管理中的两种量器。秦、西汉已存在一种既非重量又非容量的绝对价值单位"石"。只有标准米的价值单位与其容量单位数值相合,而其他状态谷物的价值单位"石"则须用大小不同的量器测量,或用不同容量数值来表示。"石"(也作"")本来是计量"禾"的重量单位,读为zjyak(后代演变为shi);但由于其在价值上与计量"米"的容量单位"担"相等,所以容量"担"亦称"石",读为tam(现在统称为dan)。